The present invention relates to a joining system for joining elements onto components, in particular for the short-time arc welding of elements, such as metal studs, onto components, such as metal sheets, having a central unit, which comprises a control device and connectable to which is at least one joining unit from a selection of different joining units, each of which comprises at least two modules.
The present invention further relates to a method of operating such a joining system. Finally, the present invention relates to a data memory, in which is stored software for effecting said method. Such a joining system and such a method of operating a joining system are generally known.
The term, joining, in the present context is to relate to all types of connection of elements to components, in particular connections of metal elements to metal components, for example by reshaping, such as riveting, or by material combining, such as welding, including short-time arc welding. Short-time arc welding is frequently referred to as stud welding, although it is not exclusively studs which are welded. A current stud welding system in industrial use is known from the brochure “Neue Tucker Technologie. Bolzenschweiβen mit System!”. [The stud welding system], Emhart TUCKER, 9/99. Stud welding is used mainly, but not exclusively, in the field of automotive engineering. There, metal elements, such as metal studs, with and without a thread, eyes, nuts etc., are welded onto the vehicle body panel. The metal elements then serve as anchors or fastening elements for fixing, for example, interior fittings.
In the case of the above-mentioned stud welding according to TUCKER, first of all an element is inserted into a welding head. This may be effected by an automatic feed device, for example by means of compressed air. The welding head then positions the element at the appropriate location on the component. Next, a preliminary current is switched on, which flows through the stud and the component. Then the element is lifted relative to the component by means of a lifting apparatus. An arc is formed. The arc current is selected in such a way that impurities, surface coatings, zinc, oils etc., are initially burnt away. There is then a switchover to the welding current. As a result of the high welding current the mutually opposing ends of the element and component start to melt. The element is then lowered back onto the component so the mutual melts intermingle. Upon reaching of the component and the short circuit of the arc, or shortly beforehand, the welding current is switched off. The melt solidifies and the weld joint is complete.
The previously mentioned stud welding system according to TUCKER comprises a central unit, to which up to five welding units are connectable. Each welding unit comprises a feed module and at least one welding module. The connection of the welding units to the central unit is effected by connecting the respective feed module to the central unit. Either one welding module is directly connected to the feed module. Alternatively, two welding modules may be connected, via a distributing guide, to the feed module. The welding modules may be welding heads, which are mounted either rigidly or movably, for example on a robot. A welding module may however alternatively take the form of a welding gun manipulatable by an operator.
In the known system, the central unit contains a power supply device, which substantially comprises a current source for providing a welding current. The central unit further comprises a control device, which controls the operation of the central unit itself as well as the welding units connected thereto. The feed modules each comprise a separate control device, which control devices are connected to the control device of the central unit by signal lines, for example in the form of optical fibres. The feed module and the welding modules connected thereto are also connected to one another by signal lines. As a result, the control device of the central unit is able to control the run-off of welding operations for all of the connected welding units. It goes without saying that the power supply lines are looped through from the power supply device of the central unit up to the respective welding modules. The feed modules further comprise a pneumatic assembly, which as a rule cooperates with an isolating device for feeding elements, which are to be welded, in an isolated manner to a connected welding module.
Different welding units are connectable to the central unit. The welding units differ from one another, first of all, in the shape of the respective elements to be welded on, whether they are studs, threaded studs, T-studs etc. Furthermore, there are differences in terms of the material, for example steel or aluminium. Moreover, there are also welding modules for producing circular weld seams for the welding-on of, for example, nuts. The welding method is referred to as MAC (magnetic arc control) welding. As already mentioned above, there are different welding modules, for example mountable welding heads and manipulatable welding guns.
For each individual process, for example steel welding of earthing studs, there is special process software. The process software is adaptable by means of freely programmable parameters to special circumstances. The process software for connected welding units is filed in an EPROM memory of the control device of the central unit.
The welding modules in the past had lifting apparatuses based on an electromagnet/spring system. Newer generations of welding modules have electric linear motors as lifting apparatuses. Welding modules having both types of lifting devices may be connected to some feed modules. Other feed modules, in particular older feed modules, on the other hand are designed exclusively for the connection of welding modules having electromagnet/spring lifting apparatuses.
From all of the above it is evident that there are many possible ways of combining welding modules, feed modules and process software. Even when the manner in which the welding system is currently configured is displayed on a display apparatus for a user, a high degree of error susceptibility still exists for incorrect configurations.
The object of the invention is to indicate a joining system for joining elements onto components, in particular for the short-time arc welding of elements onto components, as well as an associated method of operating a joining system and a data memory with software for effecting the method, with which the error susceptibility is markedly reduced. The object is achieved in the case of the joining system described at the outset in that the control device is designed so as to recognise the mutual compatibility of the at least two modules of a connected joining unit as well as the compatibility of the connected joining unit with the central unit. The object is further achieved by a method of operating a joining system for joining elements onto components, in particular for the short-time arc welding of elements, such as metal studs, onto components, such as metal sheets, wherein the joining system comprises a central unit with a control device and wherein there is connectable to the central unit at least one joining unit from a selection of different joining units, each of which comprises at least two modules, having the step of recognizing the mutual compatibility of the at least two modules of a connected joining unit and/or the compatibility of the connected joining unit with the central unit. Finally, the above object is achieved by a data memory, in which software for effecting the method is stored.
By virtue of the fact that the compatibility of the two modules of a connected joining unit is recognisable, it is possible to avoid configuration errors, and in particular configuration errors which might lead to a mutual destruction of modules or a destruction of the central unit. The control device is namely capable of recognising whether, for example, a welding module connected to a feed module does actually match the feed module. In a similar manner configuration errors with regard to the configuration of the central unit, on the one hand, and a connected joining unit, on the other hand, may be avoided. Recognition of the compatibility is effected by the control device, which carries out the recognition steps in accordance with the method according to the invention. Insofar as said method is implemented as a program, a data memory having such a program stored therein also forms a refinement of the present invention.
Preferably, the control device is programmable, and the control device is further designed so as to recognise the compatibility of the connected joining unit with the programming of the control unit. Given the refinement, it is possible further to increase the operational reliability.
In particular, it is preferred to employ a control device comprising a memory, in which is stored at least one type of process software, which is used to control at least one type of connected joining unit. It is consequently advantageous when the control device recognises the compatibility of the connected joining unit with the programming of the control device in that the control device checks whether the stored type of process software is compatible with the type of connected joining unit. In this manner, a high degree of operational reliability combined with extreme versatility of the joining system may be achieved.
According to a further preferred form of construction, the control device comprises a memory, in which is stored a plurality of types of process software, which respectively are used to control at least one type of connected joining unit. In this manner, the versatility of the joining system is further increased because different types of joining units are connectable without having to reconfigure the central unit. In this case, it is particularly preferred when the control device, in dependence upon the connected type of joining unit, selects from a plurality of types of process software the type, which is compatible with the connected joining unit, for operation. In this manner the operation and, in particular, the selection of the “correct” process software may be automated. Accordingly, the operational reliability is increased even further.
According to a particularly preferred embodiment, access to at least one type of stored process software is generally disabled but may be enabled by means of a code. This aspect is regarded as a separate invention, independently of the above-mentioned compatibility checks between modules of the joining unit and the joining unit and the central unit. By virtue of this measure it is possible to store in the memory a plurality of types or all different types of process software, but upon selling of the system it is possible to disable access to a part of the stored process software. This means that for the control device the disabled type of stored process software is regarded as non-existent. It is only through entry of a code that said type of stored process software may then be enabled. Only with enabling is said type of process software available for operation. During a compatibility check between connected joining unit and the stored types of process software, only enabled process software is considered. In other words, the compatibility check may produce a negative result, even when compatible process software is stored. This is the case when said process software is still disabled. By virtue of this measure it is possible to store all types of process software for all versions of joining systems but disable access to at least some types of process software. Individual types of process software may then be enabled by entering codes which are suitable in each case. Thus, on the whole, the reconfiguration effort is reduced.
According to a further preferred embodiment, a previously defined process parameter block type exists for each type of process software. The types of parameter blocks may differ depending on the type of process software. Many parameters are contained in one type of parameter block, others not. In this case, it is particularly preferred for each type of stored process software, a plurality of parameter blocks of the same type are stored in a memory of the control device. In this manner it is possible to operate one and the same type of process software differently by means of different parameter blocks in order to be able to take account of requirements which differ from welding operation to welding operation.
It is moreover of particular advantage when the control device in dependence upon the connected type of joining unit selects a parameter block type and offers programming exclusively of the parameters which are contained in the selected parameter block type. In this manner the programming for individual welding locations of a specific type of process software may be simplified. In particular, the repeated polling of parameters, which are not contained at all in the parameter block type, is prevented during the programming of parameter blocks of the same type for successive welding operations within an overall process. In the prior art on the other hand, every single parameter is polled during the programming of the parameters for each welding operation.
According to a further embodiment, in the course of operation the control device at intervals repeats the process of recognition of the mutual compatibility of the at least two modules of a connected joining unit as well as the compatibility of the connected joining unit with the central unit. It is thereby guaranteed that an incorrect configuration is recognised even if in the course of operation a welding module, for example, is exchanged.
On the whole, it is also preferred when the modules of a joining unit are connected to one another. This is the case, for example, in the known welding system according to TUCKER, as mentioned at the outset. Furthermore, it is particularly preferred when one of the two modules is connected to the central unit and the module, which is connected to the one module, is recognisable via the one module in the control device of the central unit. In other words, given this form of construction, despite the “serial” interconnection of the two modules, of which only one is connected to the central unit, it is possible to recognise both modules. For this purpose, signal lines are preferably provided between the modules and between the one module and the central unit. Recognition is effected by a communication between the units and/or modules by means of suitable protocols via the signal lines.
It is further preferred when the two modules of a joining unit are a feed module and a joining module, wherein the feed module is designed so as to feed elements to be joined to the joining module, and wherein the joining module is designed so as to effect a joined connection of an element, which respectively is fed, to a component. In particular, it is preferred when the two modules are a feed module and a welding module for short-time arc welding. In this case it is particularly preferred when the feed module is designed so as to supply two joining modules with elements to be joined. A distributing guide may be provided between the feed module and the joining modules for this purpose.
On the whole, it is moreover preferred when the memory of the control device is a flash memory. In this manner, large data quantities, for example including all types of process software, may be permanently stored and the data are maintained even in the event of disconnection of the power supply. Furthermore, a flash memory may be reprogrammed comparatively easily. For this purpose, it may be advantageous to provide on the central unit an interface for the connection of a computer, for example a notebook. It is self-evident that the features described above and yet to be described below are usable not only in the combination indicated in each case but also in other combinations or independently without departing from the scope of the present invention.